Manufacture of 1-aminoanthraquinone-2-sulphonic acid



Patented Aug. 16, 1932 curr es stares ALBIN PETER, 0E BASEL, SWITZERLAND, ASSIGNOR TO THE EIEM 0E oHEMIoAE wonxs EoEMEELY sannoz, or BASEL, 1 SWITZERLAND MANUFACTURE OF 1aimmonnmnnneumonn-z-surirHome now No Drawing. Application filed. March 5, 1931, Serialll'c. 520,471, and. in Germany IIIarch 11, 1930 known. According to the process described in the German Patent No. 489,460, this sulphonic acid is prepared by baking the acid sulphate of l-aminoanthraquinone and it is 10 stated therein that by using raw aminoanthraquinone the yield is of the theory, whilst by using an aminoanthraquinone that has been recrystallized from nitrobenzene about of thetheory is obtained. Ac cording to the British Patent No. 311,977 it is possible to avoid the purification of the aminoanthraquinone by mixing before heating the acid sulphate with oxalic acid.

The aminoanthraquinone can also be sulphonated by heating it with fuming sulphu- .ric acid, but as said in the German Patent 484,997 it is necessary to add to the melt a certain amount of a sulphate, such as sodium or potassium sulphate, in order to avoid the formation of disulphonic acid and of aminooxysulphonic acid and to obtain the highest yield of 1-aminoanthraquinone-2-sulphonic acid which is about 90% of the theory.

The first two processes cited above possess, compared to that of the German Patent No. 484,997 some advantages. Thus, it is possible to prepare.1-aminoanthraquinone-2- sulphonic acid without using fuming sulphuric acid or with a smaller quantity of sulphuric acid.

Patent No. 489,460 uses as starting material an aminoanthraquinone which has been purified. by recrystallization from nitrobenzene in order to separate it from inorganic impurities, as otherwise the yield of sulphonic acid reaches only about 7 5%, and the sulphonic acid obtained forms a hard cake which is difficult to work up. Although it may be possible to obviate these drawbacks by adding to the baking mass some oxalic acid, the transformation of ami'noanthraquinone into its acid sulphate is a disagreeable operation that needs a special apparatus for evaporatingto dryness under. a continuous But they also show somedrawbacks. The process, of the German stirring the pap of aminoanthraquinone and aqueous sulphuric acid. i A I It has now been found hat it is possible to prepare 1-aminoanthraquinone2sulphonicacid in a very simple manner by mixing dry finely powdered l-ami-noanthraquinone with'such a quantity of a dry acidalkalim'etal sulphate that on eachmoleculeofiamino anthraquinone at least i one molecule of-sulg phuricacid will be present, heating the mixture thus prepared in a'suitable stove, spread; out therein in thin layersjto a-tempera'ture betweenj210 and 240 C. and driving offthe T water steam produced, by means of'a current of gas or by evacuating the, stove. In this way raw 1-aminoanthraquinonee2 sulphonic acid is obtained in form ofa loose brown powder from which a small black residue isse arated by washing out in'waterand filtering. The yield is 90',95%-of the theory.

From thef U.,IS- Patent No. 885,248 where in l-aminoanthraquinone by heating with bisulphate is transformed into indanthrene, which reaction takes place at temperatures above 240 0., andfrom the German Patent No- 489,460 wherein the formation of polymolecular condensation products from raw aminoanthraquinone which usually contains inorganic catalyzers is disclosed, there could not be foreseen or derived that between 210 and 240 C(the bisulphate acts only as a sul-' phonating agent.

In view of the above statements, the new process possesses the further advantage, that the presence of heavy metal salts, such as iron, copper, lead and mercury salts doesnot affect the yield of sulphonic acid. This is especiale ly of a great importance for the technical use 1 V of this process, as it allows the use of raw .aminoanthraquinone and simple dBVICGS;

The present process, as compared to the known ones, represents, therefore, a great technical progress.

The improved process is illustrated by the I following example which is not limitative, the parts being by weight. 7

44.6 parts of finely powdered l-aminoanthraquinone are thoroughly mixed with 55.5

' can partsof sodium bisulphate, containing 21.6

parts of sulphuric acid, and spreadout in thin layersin a suitable stove; The mixture isvthen heated therein in vacuo for 3 hours' at 215220 0., cooled down and the loose brown mass obtained is boiled with 1000 parts of water. By filtering thesolution, a small quantity of an insoluble black residue is separated and the sodium salt of l aminoanthraquinone-Q-sulphonic acid is isolated by means of common salt. The product obtained after drying constitutes, according to the conditions of crystallizatioma yellow, red or red brown powder.

In this example, instead of sodium bisul phate, potassium or ammonium bisulphate be used. What I claimis:- e

1-. A process for the preparation of v laminoanthraquinone-2-sulphonic acid, consistingin heating \to 210-240 C. a mixture of 'l-aminoanthraquinone with such a quan-- tity of anacidallgali sulphatethat on each molecule of aminoanthraquinoneat least one mixture of lraminoanthraquinone with such my name this 20th day molecule of sulphuric acid will be present, While the water during the heating.

2. A process for sisting in heatingin vacuo to 210240 C. a

aquantity ofan-acid alkali sulphate that on each molecule of aminoanthraquinone at least one moleculeof sulphuric acid will be present. In witness whereof I ha e hereunto signed of February, 1931.

ALBIN PETER.

steam formed is eliminated the preparation of 1 1 aminoanthraquinone-2-sulphonio acid, con-c 

